Rotary piston compressor with rotary pistons arranged eccentrically one within the other



Feb. 1, 1966 F LUCK 3,232,523

ROTARY PISTON COMPRESSOR WITH ROTARY PISTONS ARRANGED ECCENTRICALLY ONE WITHIN THE OTHER Filed Nov. 20, 1963 2 Sheets-Sheet 1 Feb. 1, 1966 F. LUCK ROTARY PISTON COMPRESSOR WITH ROTARY PISTONS ARR ECCENTRICALLY ONE WITHIN THE OTHER Filed Nov. 20, 1963 ANGED 2 Sheets-Sheet 2 Jiwemor: 75194, t; .4 u'k/r United States Patent 3,232,523 ROTARY FISTQN CGMPRESSOR WITH ROTARY PESTONS GED ECCENTRICALLY ONE WETHIN T HE OTHER Friedrich Liich, Berlin-Frohnan, Germany, assignor to Borsig Alrtiengeseilschaft, Berlin-Tegel, and to Wankel G.rn.b.H., Lindau (llodensee), Germany Filed Nov. 26, 1963, fier. No. 325,105 Claims priority, application Germany, Nov. 23, 1962, B 69,741 6 Claims. (El. 23tl-139) The present invention relates to a rotary piston compressor which, for high diiferences in pressure and high circumferential speeds, is provided with two rotary pis tons arranged eccentrically one within the other and coupled to each other, for instance by additional gears, the outer rotary piston being open at one end face and supporting a shaft journal at the other end face.

Rotary piston machines have become known which are suitable for medium pressure conditions and differences in pressure at mgh circumferential speeds and are also suitable for high dififerences in pressure at relatively low circumferential speeds.

With the first-mentioned designs as disclosed, for instance in German Patent 1,086,244, in the interior of the inner rotary piston there are, in addition to the central hearing therefor, also provided the suction as well as the pressure conduits. This arrangement, however, is not suitable when the machine is to be subjected to high differences in the pressure. In such instances, it would be necessary to reinforce the bearing to such an extent that the necessary space for the provision of the two conduits would be lacking.

According to the above-mentioned second design as described, for instance, in my copending application Ser. No. 253,845, filed January 25, 1963, which concerns a rotary piston machine sealed substantially by gaps, the question of space for the provision of the two conduits has been solved by arranging the conduits in the housing end Wall which thus do not interfere with the bearing for the inner rotary piston. This type of machine, however, is somewhat limited as to its speed, because the main bearing is, for reasons of sealing at the working chambers, arranged in the compressor cross-sectional plane, whereby it becomes necessary to give the rotary piston machine a greater diameter, If high speeds are to be realized, the main hearing would have to be reduced and provided at another place. In such an instance, however, the overall design of the machine would have to be changed, particularly the gap sealing and the design of the conduits.

It is, therefore, an object of the present invention to provide a rotary piston compressor with rotary pistons arranged eccentrically with regard to each other, in which the rotary piston body will be so journalled that the life of the hearing will practically not be afiected, while on the other hand, an efiicient gas seal and a favorable design of the conduit means will be assured.

It is also an object of this invention to provide a rotary piston machine as set forth in the preceding paragraph, which will make it possible, without additional expenses, to mount a drive motor on the shaft of the outer rotary piston.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

FIGURE 1 represents a longitudinal section through a rotary piston machine according to the present invention, said section being taken along the line II of FIG- URE 2;

FIGURE 2 is a cross-section through the machine of FIGURE 1 as taken along the line 11-11 of FIGURE 1;

FIGURE 3 illustrates in section on a larger scale than FIGURE 1 the central right hand portion of FIGURE 1.

The problem underlying the present invention has been solved in conformity with the present invention by the combination of two features, viz (a) the pressure conduit only has been retained in the interior of the inner rotary piston while being passed around the large inner bearing in View of the eccentricity of the rotors, so that it will lead into the housing lid and (b) the main bearing of the outer rotary piston is located adjacent the compressorcross-sectional plane. The considerable increase inherent thereto in the bearing load while simultaneously the bear ing diameter has been reduced, is, to a great extent, compensated for by producing a favorable lever ratio by means of the fact that the bearing on the input side has been moved out further. At the same time, this creates the possibility of mounting the drive motor between the two bearings for the outer rotary piston.

More specifically, with reference to the drawings, the arrangement shown therein comprises an outer rotary piston 1 having two teeth and being composed of the central portion 1a and the end walls 1!) and 1c. The rotary piston 1 has a shaft or stud 2 connected thereto which, in view of the high transverse pressures at the simultaneously occurring high rotary speeds, is provided with two spaced transverse bearings 3 and 4, respectively. It is between these hearings 3 and 4 that the rotor 5a of the drive motor 5 is arranged and drivingly connected to shaft 2, said drive motor having a stator 5b. The inner rotary piston 6 is, by means of a pair of gears 7 coupled to the outer rotary piston 1 and by means of a stud 6a arranged on the inner side of end wall 6b, is journalled on a housing part 9 extending into the interior of the stud 6a. Also, the pressure conduit 10 is journalled in housing part 9 and extends around said bearing 8 while leading to the end face of the housing. The end walls 1b and 1c of the outer rotary piston 1 are provided with inlet slots 11, whereas outlet slots 12 are provided in the peripheral surface 6a of the inner rotary piston 6. The inner rotary piston is. for instance, by means of a guiding disc 13 guided in axial direction relative to the housing part 9. By selecting a gauge ring 14 of a corresponding thickness, the proper positions of the two rotary pistons relative to each other may be adjusted. The compressor and motor are confined by a housing 15 common thereto, the lids 16 and 17 of which have an inlet opening 18 and an outlet opening 19.

The working medium intermixed with lubricating oil passes through inlet opening 18 into the housing and flows through passages through inlet slots 11- intothe working chambers 26 of the compressor. Here the work ing medium is compressed and leaves the machine through outlet slots 12, pressure conduit 10 and outlet opening 19 of the machine. In this way, the bearings 3 and 4 are lubricated and are, together with the driving motor 5, cooled in an effective manner. The lubrication of the inner rotary piston hearing as well as of the gears is effected by oil under pressure which, for instance, is passed through bore 21 into the direct vicinity of the axial bearing 13, said oil under pressure being under the gas pressure of the compressor.

More specifically, the oil under pressure passes, for instance, through bore 21 to the bearing stud 6c of the inner rotary piston 6 and from there, aided by the centrifugal force passes on one hand to hearing 8 from where it can flow oil through one or more compensating bores 6d, and on the other hand flows to the axial bearing 60-13. Through the necessarily provided bearing gap in the axial bearing, the oil passes through the pair of gears 7.

The axial bearing is composed of the hollow rotary bearing st-ud6c, the stationary guiding disc 13 and the ring connected to the rotary bearing stud. The play in the bearing will be secured, as mentioned aboveby the insertion of a-fitting ring 14 of correspondingthickness. The inner rotary piston -6 consists of a single piece. The inner orhub portion of said rotary piston 6 has beendesignated Withthe reference numeral-6c, whereas that portion forming the end face is designated with the reference numeral 65. That portion of the rotary piston 6 which carries the rotor teeth has been designated with the reference numeral 6a.

It is, of course, to be understood, that the present invention is, by no means, limited to the particular construction shown in the drawing, but also comprises any modificat'ion's within the scope of the appended claims.

What I claim is:

1. A rotary piston compressor, especially for a refrigerating medium, which includes: outer and inner rotary piston means rotatably and eccentrically arranged one Within the other and drivingly connected to each other, said inner and outer piston means confining with each other chamber means varying in volume in response to a rotation thereof for receiving and compressing a medium to be compressed, one of said piston means having inlet means for admitting a medium to be compressed to said chamber means, housing means housing said outer and inner rotary piston means and having an intake port communicating with said inlet means and connectable to a supply of a medium to be compressed, said housing means also having a discharge port for discharging the compressed medium, said outer piston means being open at one end face and having a shaft journal connected to its other end face, heating means arranged in spaced relationship to each other and supporting said shaft journal at spaced portions thereof, driving motor means having a rotor arranged between said bearing means and drivingly Connected to said shaft journal, additional bearing means connected to said housing means and substantially centrally ro'tatably supporting said inner rotary piston means, and conduit means extending around said additional bearing :means and communicating with said discharge port, said inner rotary :piston means being provided with outlet means operable in response to a certain relative position of said inner and outer piston means to convey compressed medium from said chamber means to said conduit means and thereby to said discharge port.

2. A rotary piston compressor according to claim 1, which includes adjustable bearing means arranged within the interior of said inner rotary piston means for axially guiding said inner rotary piston means.

3. A rotary piston compressor according to claim 1, in which said outer rotary piston means includes end Walls, and in which said inlet means are provided in each of said end walls.

4. A rotary piston compressor, especially for a refrigerating medium, which includes: outer and inner rotary piston means rotatably and eccentrically arranged one within the other and drivingly connected to each other,

said inner and outer piston means confining with each other chamber means varying in volume in response to a rotation thereof for receiving and compressing a medium to be compressed, one of said piston means having inlet means for admitting a medium to be compressed to said chamber means, said outer piston means being open at one end face and having a shaft journal connected to its other end face, bearing means arranged in spaced relationship to each other and supporting said shaft journal at spaced portions thereof, driving motor means having a rotor arranged between said bearing means and drivingly connected to said shaft journal, housing means common to said motor meansand said inner and outer piston means and housing the same including said bearing means, said housing means having that end portion thereof which is remote from said inner and outer piston means provided with at inlet port communicating with said inlet means around said motor means and connectable to a supply of a medium tobe compressed, said housing means also having a discharge port for discharging the medium compressed in said chamber means, additional bearing means connected to said housing means and substantially centrally rotatably supporting said inner rotary piston means, and conduit means extending around said addi tional bearing means and communicating with said discharge port, said inner rotary piston means being provided with outlet means operable in response to a certain relative position of said inner and outer piston means to convey compressed medium from said chamber means to said conduit means and thereby to said discharge port.

5. A rotary piston compressor according to claim 4, in which said housing means housing said motor means and said inner and outer piston means is to its major extent cylindrical, said motor means and said inner and outer rotary piston means forming a single unit.

6. A rotary piston compressor according to claim 1, which includes gear means drivingly interconnecting said inner and outer rotary piston means, and also includes lubricant conveying conduit means communicating with said gear means and with all of said bearing means for conveying oil under pressure thereto, said conduit means being under the pressure of the medium compressed by said compressor.

11/ 1956 Germany. 8/ 1960 Germany.

MARK NEWMAN, Primary Examiner.

V. J. GOODLIN, Assistant Examiner. 

1. A ROTARY PISTON COMPRESSOR, ESPECIALLY FOR A REFRIGERATING MEDIUM, WHICH INCLUDES: OUTER AND INNER ROTARY PISTON MEANS ROTATABLY AND ECCENTRICALLY ARRANGED ONE WITHIN THE OTHER AND DRIVINGLY CONNECTED TO EACH OTHER, SAID INNER AND OUTER PISTON MEANS CONFINING WITH EACH OTHER CHAMBER MEANS VARYING IN VOLUME IN RESPONSE TO A ROTATION THEREOF FOR RECEIVING AND COMPRESSING A MEDIUM TO BE COMPRESSED, ONE OF SAID PISTON MEANS HAVING INLET MEANS FOR ADMITTING A MEDIUM TO BE COMPRESSED TO SAID CHAMBER MEANS, HOUSING MEANS HOUSING SAID OUTER AND INNER ROTARY PISTON MEANS AND HAVING AN INTAKE PORT COMMUNICATING WITH SAID INLET MEANS AND CONNECTABLE TO A SUPPLY OF A MEDIUM TO BE COMPRESSED, SAID HOUSING MEANS ALSO HAVING A DISCHARGE PORT FOR DISCHARGING THE COMPRESSED MEDIUM, SAID OUTER PISTON MEANS BEING OPEN AT ONE END FACE AND HAVING A SHAFT JOURNAL CONNECTED TO IS OTHER END FACE, BEARING MENS ARRANGED IN SPACED RELATIONSHIP TO EACH OTHER AND SUPPORTING SAID SHAFT JOURNAL AT SPACED PORTIONS THEREOF, DRIVING MOTOR MEANS HAVING A ROTOR ARRANGED BETWEEN SAID BEARING MEANS AND DRIVINGLY CONNECTED TO SAID SHAFT JOURNAL, ADDITIONAL BEARING MEANS CONNECTED TO SAID HOUSING MEANS AND SUBSTANTIALLY CENTRALLY ROTATABLY SUPPORTING SAID INNER ROTARY PISTON MEANS, AND CONDUIT MEANS EXTENDING AROUND SAID ADDITIONAL BEARING MEANS AND COMMUNICATING WITH SAID DISCHARGE PORT, SAID INNER ROTARY PISTON MEANS BEING PROVIDED WITH OUTLET MEAND OPERABLE IN RESPONSE TO A CERTAIN RELATIVE POSITION OF SAID INNER AND OUTER PISTON MEANS TO CONVEY COMPRESSED MEDIUM FROM SAID CHAMBER MEANS TO SAID CONDUIT MEANS AND THEREBY TO SAID DISCHARGE PORT. 